A cotton-based room-temperature phosphorescent material, its preparation method and application

Abstract

The present invention discloses a cotton-based room temperature phosphorescent material, its preparation method and application. The preparation method of the cotton-based room temperature phosphorescent material comprises the following steps: carrying out a grafting reaction on degreased cotton and a phenylboronic acid derivative to obtain a grafted product. Preferably, before the grafting reaction, the degreased cotton is first subjected to oxidation treatment and then reduction treatment. Preferably, after obtaining the grafted product, the grafted product is subjected to silicone oil adsorption or silanol grafting treatment. The present invention for the first time uses the natural material degreased cotton to prepare a variety of room temperature phosphorescent materials, the longest lifespan of the materials reaches 1.04 seconds, and has a long afterglow emission after turning off the ultraviolet lamp. The room temperature phosphorescent material of the present invention can be made into ink or coating, written on materials such as gauze, and can be applied to the fields of anti-counterfeiting and intelligent textiles.

Description

Technical Field

[0001] The present invention relates to the technical field of phosphorescent materials, and particularly relates to a cotton-based room temperature phosphorescent material, a preparation method thereof, and an application thereof. Background Art

[0002] Phosphorescence is a phenomenon of slow photoluminescence, characterized in that when the excitation light irradiation stops, the luminescence phenomenon can still persist, and it has the advantages of long luminescence lifetime, large Stokes shift, diverse excitation properties, etc. In recent years, room temperature phosphorescent (RTP) materials with long lifetimes have been widely studied due to their broad application prospects in the fields of anti-counterfeiting, sensing, information encryption, biological imaging, etc. Narrowing the energy gap between the excited singlet state (S1) and the triplet state (Tn), increasing the intersystem crossing rate (ISC), increasing the spin-orbit coupling (SOC), and stable triplet emission are the core elements for improving RTP performance.

[0003] At present, researchers have developed many design methods to improve the RTP performance of phosphorescent materials. For example, by introducing halogen bonds, aromatic carbonyl groups or heavy metal atoms into the structure of RTP materials to improve SOC, thereby promoting the ISC process; or by host-guest interactions, hydrogen bond interactions, crystal engineering, constructing porous organic frameworks to inhibit the energy loss of non-radiative decay. Among them, polymer room temperature phosphorescent materials have attracted much attention due to their good processability, easy synthesis, and thermal stability. The polymer matrix can protect the phosphor from the influence of oxygen by various methods to inhibit the non-radiative decay of triplet excitons, and various interactions such as hydrogen bonds, covalent bonds, and ionic bonds can be used between the phosphor and the polymer to inhibit the vibration and rotation of the phosphor. However, most organic materials need to be prepared through complex and time-consuming chemical processes, and a large amount of toxic reagents often need to be added during the reaction process. The polymer matrix used needs to be finely processed and is difficult to degrade. Therefore, developing new natural polymer RTP materials to solve the above problems is of great significance for the practical application of room temperature phosphorescent materials and reducing environmental pollution. Summary of the Invention

[0004] The main object of the present invention is to provide a cotton-based room temperature phosphorescent material, a preparation method thereof, and an application thereof.

[0005] To achieve the above object, the present invention provides a preparation method of a cotton-based room temperature phosphorescent material, comprising the following steps: grafting reaction is carried out between degreased cotton and a phenylboronic acid derivative to obtain a grafted product.

[0006] Further, the phenylboronic acid derivative is selected from any one of 4-carboxyphenylboronic acid, 4,4'-biphenyldiboronic acid, 4-biphenylboronic acid, and 4'-bromo-4-biphenylboronic acid.

[0007] Further, the operation process of the grafting reaction is as follows: Immerse the degreased cotton in deionized water, add a tetrahydrofuran solution of a phenylboronic acid derivative, then add ammonia water, and then stir at 80 °C for 1 h. Finally, filter and dry to obtain the room-temperature phosphorescent material.

[0008] Further, the mass ratio of degreased cotton to 4-carboxyphenylboronic acid is 100:4, and the mass ratio of degreased cotton to 4,4'-biphenyldiboronic acid or 4-biphenylboronic acid or 4'-bromo-4-biphenylboronic acid is 100:1.

[0009] The main component of cotton is cellulose, which is a natural polymer material. Cotton contains a large number of uniformly arranged hydroxyl groups. These hydroxyl groups not only provide a strong hydrogen bond network to inhibit non-radiative transitions and promote excitons to return from the triplet state to the ground state, but also are easily modified by other functional groups. Although cellulose has a weak phenomenon of aggregation-triggered emission, it is difficult to observe in cotton, and this weak intrinsic luminescence is difficult to meet the actual production and living needs.

[0010] The present invention synthesizes a series of room-temperature phosphorescent materials through water-phase B-O click chemical reactions, through the hydrogen bond interaction between boric acid molecules and degreased cotton and the rigid structure of degreased cotton. Under alkaline conditions, boric acid small molecules are easy to react with the hydroxyl groups in cotton to form borate bonds in water phase or other common solvents. Under the action of hydrogen bond interaction and rigid environment, the movement of boric acid chromophores is inhibited, enhancing the intersystem crossing (ISC) process, thereby promoting phosphorescence emission. By selecting phenylboronic acid derivatives with different structures to tune the conjugation degree of boric acid molecules, multicolor room-temperature phosphorescent emission can be achieved.

[0011] Further, before the grafting reaction, the degreased cotton is first subjected to oxidation treatment and reduction treatment in sequence.

[0012] Further, the operation process of the oxidation treatment is as follows: Add degreased cotton and sodium periodate to deionized water, react in the dark at 60 °C for 10 h, then add ethylene glycol to stop the reaction, and finally dialyze, filter, and dry.

[0013] Further, the operation process of the reduction treatment is as follows: Add the oxidized degreased cotton and sodium borohydride to deionized water, stir at room temperature for 4 h, and finally dialyze, centrifuge, and dry.

[0014] Further, the mass ratio of degreased cotton to sodium periodate and sodium borohydride is 2.58:3.21:8.

[0015] Although cellulose contains a large number of hydroxyl groups, its solubility in water is poor. In the present invention, a directional redox technology is adopted. Sodium periodate is used to selectively oxidize two secondary hydroxyl groups at the 2nd and 3rd positions on the glucosyl ring of cotton fibers, and then the oxidized hydroxyl groups are reduced by sodium borohydride, which can greatly increase the water solubility and reactivity of the hydroxyl groups, improve the activity of hydroxyl groups at specific sites on absorbent cotton, and greatly improve the lifetime and quantum yield of room temperature phosphorescent materials.

[0016] Further, after obtaining the grafted product, the grafted product is subjected to silicone oil adsorption or silanol grafting treatment.

[0017] Further, the operation process of the silicone oil adsorption is as follows: The grafted product is soaked in amino silicone oil for 2 h, and then taken out for drying treatment;

[0018] The operation process of the silanol grafting treatment is as follows: n-octyltriethoxysilane is added to a mixed solution of ethanol and water to hydrolyze to form silanol, then the grafted product is added and reacted for 2 h, and finally taken out for heating and drying treatment.

[0019] Further, the volume ratio of ethanol to water is 9:1.

[0020] In the present invention, the room temperature phosphorescent material is combined with silicone oil and silane by means of physical adsorption and chemical grafting, which can improve the water resistance of the material.

[0021] Room temperature phosphorescent materials are usually easily quenched by oxygen and water. Since cotton constructs a micro-rigid environment, it resists the interference of oxygen to a certain extent, but it is greatly affected by water. Amino silicone oil emulsion can form a protective layer on the surface of cotton, effectively blocking the penetration of moisture and improving the waterproof performance of the product. n-Octyltriethoxysilane hydrolyzes into silanol in a mixed solution of ethanol and water, forms hydrogen bonds by combining with the hydroxyl groups on the cotton surface, and forms a polysiloxane network through intermolecular self-crosslinking. After heating, it can be stably grafted on the cotton surface, reducing the surface free energy to generate a hydrophobic interface, which can also enhance the waterproof property of the material.

[0022] The present invention also provides a room temperature phosphorescent material based on cotton, which is prepared according to the above preparation method.

[0023] The present invention also provides the application of the above room temperature phosphorescent material based on cotton in the preparation of ink or coating.

[0024] The beneficial effects of the present invention are embodied in:

[0025] The present invention first uses natural material absorbent cotton to prepare a variety of room temperature phosphorescent materials. The longest lifetime of the materials reaches 1.04 s, and has a long afterglow emission after turning off the ultraviolet lamp.

[0026] The present invention can regulate the afterglow color by controlling the conjugation degree of grafted phenylboronic acid, and the product has excitation wavelength dependence, and its phosphorescence emission range can be changed by changing the excitation wavelength.

[0027] The present invention enhances the water resistance of the room temperature phosphorescent material through physical adsorption and chemical grafting. The material has long-term stability, and its phosphorescence emission can be restored by heating after being eroded by water, and it has high reusability.

[0028] The room temperature phosphorescent material of the present invention can be made into ink or coating and written on materials such as gauze, and can be applied to the fields of anti-counterfeiting and intelligent textiles.

[0029] The present invention uses natural polymer materials as the matrix, the raw materials are low in price and green and environmentally friendly, uses water as the main solvent, and the preparation process is simple, with wide adaptability and broad development prospects. Description of the Drawings

[0030] Figure 1 It is the fluorescence and phosphorescence spectra of M1.

[0031] Figure 2 It is the fluorescence and phosphorescence spectra of M2.

[0032] Figure 3 It is the fluorescence and phosphorescence spectra of M3.

[0033] Figure 4 It is the fluorescence and phosphorescence spectra of M4.

[0034] Figure 5 It is the fluorescence and phosphorescence spectra of M5.

[0035] Figure 6 It is the structural characterization diagram of the material (in the figure, Figure a is the infrared spectra of different components and the subtraction spectrum of M5 and modified cotton, Figure b is the X-ray diffraction spectra of degreased cotton and modified cotton, Figure c is the X-ray photoelectron spectroscopy carbon spectrum, and Figure d is the X-ray photoelectron spectroscopy boron spectrum).

[0036] Figure 7 It is the scanning electron microscope and application photos of the material (in the figure, Figure a is the scanning electron microscope of degreased cotton, Figure b is the scanning electron microscope of M2, Figures c, e, and g are the photos of writing M5 made into ink on gauze under natural light, under 365 nm ultraviolet light, and after being illuminated by 254 nm ultraviolet light for 2 s and then turned off, and Figures d, f, and h are the photos of injecting M5 made into ink on gauze with a syringe under natural light, under 365 nm ultraviolet light, and after being illuminated by 254 nm ultraviolet light for 2 s and then turned off).

[0037] Figure 8For the initial M2, the phosphorescence spectra after 5 minutes of water vapor fumigation and 2 minutes and 4 minutes of drying in a 100 °C drying oven.

[0038] Figure 9 The waterproof control phosphorescence spectra of the materials (in the figure, Figure a is the phosphorescence emission spectra of M6 and M6 soaked in water, Figure b is the phosphorescence emission spectra of M7 and M7 soaked in water, and Figure c is the phosphorescence emission spectra of M5 and M5 soaked in water).

[0039] Figure 10 The phosphorescence spectra of M1 under illumination with different excitation wavelengths. Detailed implementation manners

[0040] To make the technical solutions of the present invention clearer and more understandable to those skilled in the art, the following examples are listed for illustration. It should be noted that the following examples do not limit the protection scope required by the present invention.

[0041] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial channels or can be obtained by existing known methods; unless otherwise specified, the methods used in the embodiments of the present invention are all methods mastered by those skilled in the art. Among them: 4-carboxyphenylboronic acid (98%) was purchased from the Annegene reagent platform. 4,4'-biphenyldiboronic acid (>95%) and 4'-bromo-4-biphenylboronic acid (97%) were purchased from the Aladdin reagent platform. 4-biphenylboronic acid (98%), sodium periodate (99.5%), and n-octyltriethoxysilane (97%) were purchased from the Macklin reagent platform. Sodium borohydride (NaBH 4 ) and ethylene glycol were purchased from the Sinopharm Chemical Reagent Co., Ltd. Amino silicone oil, model 8040A, cas: 28323-47-9, was purchased from Guangzhou Xinguan Chemical Technology Co., Ltd. Absorbent cotton, that is, cotton without fat, was purchased from Caoxian Weiguang Sanitary Materials Co., Ltd.

[0042] Example 1

[0043] Preparation of cotton-based room temperature phosphorescent material M1

[0044] Disperse 0.1 g of absorbent cotton in 10 ml of deionized water, add 1 ml of a tetrahydrofuran solution of 4-carboxyphenylboronic acid (CBa) with a concentration of 10 mg / ml, and then add 1 ml of ammonia water with a concentration of 25 wt%. Stir at 80 °C and a rotation speed of 640 r / min for 1 h, then perform filtration treatment. The obtained filter residue is dried at a vacuum degree of -0.1 Mpa and 80 °C for 12 h to obtain a grafted product, which is the cotton-based room temperature phosphorescent material M1.

[0045] Example 2

[0046] Preparation of cotton-based room temperature phosphorescent material M2

[0047] The preparation method of this example is the same as that of Example 1, except that: the tetrahydrofuran solution of 4-carboxyphenylboronic acid (CBa) is replaced with a tetrahydrofuran solution of 4,4'-biphenyldiboronic acid (Bp-dBa) with a concentration of 1 mg / ml, and the finally obtained grafted product is the room-temperature phosphorescent material M2 based on cotton.

[0048] Example 3

[0049] Preparation of room-temperature phosphorescent material M3 based on cotton

[0050] The preparation method of this example is the same as that of Example 1, except that: the tetrahydrofuran solution of 4-carboxyphenylboronic acid (CBa) is replaced with a tetrahydrofuran solution of 4-biphenylboronic acid (BpBa) with a concentration of 1 mg / ml, and the finally obtained grafted product is the room-temperature phosphorescent material M3 based on cotton.

[0051] Example 4

[0052] Preparation of room-temperature phosphorescent material M4 based on cotton

[0053] The preparation method of this example is the same as that of Example 1, except that: the tetrahydrofuran solution of 4-carboxyphenylboronic acid (CBa) is replaced with a tetrahydrofuran solution of 4'-bromo-4-biphenylboronic acid (BrBpBa) with a concentration of 1 mg / ml, and the finally obtained grafted product is the room-temperature phosphorescent material M4 based on cotton.

[0054] Example 5

[0055] Preparation of room-temperature phosphorescent material M5 based on cotton

[0056] The preparation method of this example is the same as that of Example 2, except that: the absorbent cotton is replaced with modified cotton;

[0057] The preparation method of the modified cotton is as follows: Add 2.58 g of absorbent cotton and 3.21 g of sodium periodate to 100 ml of deionized water, react in the dark at 60 °C for 10 h, add 10 ml of ethylene glycol to stop the reaction, then put the reaction mixture into a dialysis bag with a molecular weight cut-off of 8000, and dialyze with pure water as the dialysis solution at room temperature for 12 h to remove impurities. Repeat three times. Finally, filter the dialyzed reaction mixture, and dry the obtained filter residue at room temperature and a vacuum degree of -0.1 Mpa for 12 h to obtain the oxidized absorbent cotton;

[0058] Dissolve 1.5 g of peroxidized degreased cotton in 30 ml of deionized water, add 0.8 g of sodium borohydride, stir and react at room temperature and a rotation speed of 640 r / min for 4 h. Then, put the reaction mixture into a dialysis bag with a molecular weight cut-off of 8000, and use pure water as the dialysis solution to dialyze at room temperature for 12 h to remove impurities. Repeat this process three times. Finally, centrifuge the dialyzed reaction mixture at a rotation speed of 6000 r / min, and dry the obtained centrifuged product at room temperature and a vacuum degree of -0.1 Mpa for 12 h to obtain the modified cotton.

[0059] The finally obtained grafted product is the room-temperature phosphorescent material M5 based on cotton.

[0060] Example 6

[0061] Preparation of Room-Temperature Phosphorescent Material M6 Based on Cotton

[0062] The preparation method of this example is the same as that of Example 5, except that after obtaining the grafted product, the grafted product is further subjected to silicone oil adsorption treatment. The specific operation process is as follows: Immerse 0.1 g of the grafted product in 5 g of amino silicone oil for 2 h, then filter out the soaked grafted product, and dry it at 80 °C and a vacuum degree of -0.1 Mpa for 12 h to obtain the room-temperature phosphorescent material M6 based on cotton.

[0063] Example 7

[0064] Preparation of Room-Temperature Phosphorescent Material M7 Based on Cotton

[0065] The preparation method of this example is the same as that of Example 5, except that after obtaining the grafted product, the grafted product is further subjected to silanol grafting treatment. The specific operation process is as follows: Add 5 g of n-octyltriethoxysilane to a mixed solution of 10 ml of ethanol and water (the volume ratio of ethanol to water is 9:1) to hydrolyze to form silanol, then add 0.1 g of the grafted product and react for 2 h. Finally, filter out the reacted grafted product and dry it at 80 °C and a vacuum degree of -0.1 Mpa for 12 h to obtain the room-temperature phosphorescent material M7 based on cotton.

[0066] Experimental Example 1

[0067] Optical Property Test of Room-Temperature Phosphorescent Material Based on Cotton

[0068] Test the optical properties of the room-temperature phosphorescent materials M1 - M5 based on cotton prepared in the above examples. Among them, the room-temperature phosphorescence spectrum is measured using a Hitachi F-4600 spectrophotometer, and the phosphorescence lifetime is measured using a steady-state and transient fluorescence spectrometer (Fluorolog-3-Tau and deltaflex). The results are shown in Table 1 below, and the fluorescence and phosphorescence spectra of M1 to M5 are as Figures 1 to 5 shown.

[0069] Table 1

[0070]

[0071] Structural characterization and analysis were carried out on degreased cotton, modified cotton, and M5, and the results are as Figure 6 shown, where:

[0072] Figure a is the infrared spectra of different components and the subtraction spectrum of M5 and modified cotton. The stretching vibration peaks of hydroxyl groups are at 3600 - 3150 cm -1 The stretching vibration peaks of C-H are at 3000 - 2800 cm -1 The stretching vibration peaks of C-O are at 1050 - 950 cm -1 It can be seen that the absorption peaks of M5 are stronger in the range of 1430 - 1310 cm -1 , which proves that a large number of B-O bonds are formed between the phenylboronic acid chromophore and degreased cotton. From the subtraction spectrum, it can be seen that small molecules are successfully grafted onto cotton.

[0073] Figure b is the X-ray diffraction spectra of degreased cotton and modified cotton. By comparing the XRD patterns of modified cotton, it can be seen that degreased cotton only has an amorphous broad peak caused by the polymer, while modified cotton has a more refined peak structure, indicating that redox modification changes the crystalline structure of cotton to form a harder microenvironment.

[0074] Figure c is the X-ray photoelectron spectroscopy carbon spectrum, and Figure d is the X-ray photoelectron spectroscopy boron spectrum. The XPS spectra show that the binding energies of C-O-B covalent bonds and B-O covalent bonds are 289.3 eV and 192.9 eV respectively, indicating the successful progress of the grafting reaction.

[0075] In addition, scanning electron microscopy observations were carried out on degreased cotton and modified cotton. Referring to Figure 7 Figures a and b, it can be seen that the fiber structure of degreased cotton is not changed by the grafting reaction. M5 was made into an ink (100 mg of M5 was dissolved in 2 ml of deionized water), and it was written with a brush and injected with a syringe on gauze respectively. The photos of the gauze under natural light, under 365 nm ultraviolet light irradiation, and after being irradiated with 254 nm ultraviolet light for 2 s and then turned off are as Figure 7 shown in Figures c to h. It can be seen that after being irradiated with 254 nm ultraviolet light for 2 s and then turning off the ultraviolet light, afterglow emission was observed.

[0076] Figure 10 is the phosphorescence spectrum of M1 under illumination at different excitation wavelengths. It can be observed that as the excitation light wavelength increases, the spectrum gradually redshifts.

[0077] Experimental Example 2

[0078] Waterproof performance test of cotton-based room temperature phosphorescent materials

[0079] Figure 8 The phosphorescence emission spectra of M2 at the initial stage, after being fumigated with water vapor for 5 minutes, and dried in an oven at 100 °C for 2 minutes and 4 minutes. It can be observed that the phosphorescence intensity of M2 decreases after humidification and gradually recovers after drying.

[0080] Figure 9 The phosphorescence emission spectra for the waterproof control of the material. In the figure, Figure a shows the phosphorescence emission spectra of M6 and M6 soaked in water, Figure b shows the phosphorescence emission spectra of M7 and M7 soaked in water, and Figure c shows the phosphorescence emission spectra of M5 and M5 soaked in water. It can be observed that the phosphorescence of M5 basically disappears after being soaked in deionized water, while M6 obtained by soaking in amino silicone oil and M7 obtained by grafting with silanol still retain partial phosphorescence emission.

[0081] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a room temperature phosphorescent material based on cotton, characterized in that: The following steps are involved: The absorbent cotton and the phenylboronic acid derivative are subjected to a grafting reaction to obtain a grafted product; Before the grafting reaction, the absorbent cotton is subjected to oxidation treatment and reduction treatment in sequence. The oxidation treatment process is as follows: adding the absorbent cotton and sodium periodate into deionized water, reacting at 60° C. in the dark for 10 hours, then adding ethylene glycol to stop the reaction, and finally dialyzing, filtering, and drying. The reduction treatment process is as follows: adding the oxidized absorbent cotton and sodium borohydride into deionized water, stirring at room temperature for 4 hours, and finally dialyzing, centrifuging, and drying.

2. The method for preparing the cotton-based room temperature phosphorescent material according to claim 1, characterized in that: The phenylboronic acid derivative is selected from any one of 4-carboxyphenylboronic acid, 4,4'-biphenyldiboronic acid, 4-biphenylboronic acid and 4'-bromo-4-biphenylboronic acid.

3. The method for preparing a cotton-based room temperature phosphorescent material according to claim 1, characterized in that: The operation process of the grafting reaction is: soaking absorbent cotton in deionized water, adding tetrahydrofuran solution of phenylboronic acid derivative, then adding ammonia water, and then stirring at 80° C. for 1 hour, and finally filtering and drying.

4. The method for preparing a cotton-based room temperature phosphorescent material according to claim 1, 2 or 3, characterized in that: After the grafted product is obtained, the grafted product is subjected to silicone oil adsorption or silanol grafting treatment.

5. The method for preparing the cotton-based room temperature phosphorescent material according to claim 4, characterized in that: The operation process of silicone oil adsorption is: soaking the grafted product in amino silicone oil for 2 hours, and then taking it out for drying; The operation process of the silanol grafting treatment is: adding n-octyltriethoxysilane to a mixture of ethanol and water, hydrolyzing to form silanol, then adding the grafted product to react for 2 hours, and finally taking it out for heating and drying treatment.

6. A cotton-based room temperature phosphorescent material, characterized in that: Prepared according to the preparation method as described in any one of claims 1 to 5.

7. Use of the cotton-based room temperature phosphorescent material as claimed in claim 6 in the preparation of ink or coating.

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